Supplementing waste heat from kilns or the like



March 25, 1941. c, P HARRls 2,235,993

SUPPLEMENTING WASTE HEAT FROM KILNS OR THE LIKE Filed Sept. 24, 1938 I INVENTOR. CA /A/ row Pflfi/PR/s.

Patented Mar. 25, 1941 UNITED STATES SUPPLEMENTING WASTE HEAT FRQM KILNS OR THE. LIKE Clinton I. Harris, Alpena, Mich, assignor to Huron Portland Cement Company, Detroit, Mich, a corporation of New York Application September 24, 1938, Serial No. 231,472

6 Claims.

This invention relates to the art of putting the waste heat from a cement kiln or the like to a useful purpose.

The hot gases and products of combustion issuing from a cement kiln have'heretofore been employed for the purpose of generating steam, to which end a boiler equipped with appropriate boiler tubes is disposed so as to make use of such hot gases. A problem, however, has presented itself, namely, that of generating sumcient steam and that of control of the amount of steam generated. A number of things may contribute to these problems, among which are the following: the demand forthe steam generated by heat, which would otherwise be wasted, may increase to a point beyond that which can be generated; more efiicient kilns may be installed, with the resuit that the waste heat is lowered to such an extent that the steam which can be generated thereby is not sufficient to meet the demand or requirements.

This invention aims to rectify conditions such as these and take advantage of the excess capacity of the fuel supplying means, such as a coal mill. Accordingly, a steam boiler is employed in association with a kiln for making use of hot gases and products of combustion which would otherwise be wasted, and a by-pass for fuel is arranged between the fuel feeding device and the chamber or compartment at the opposite end of the kiln which receives the products of combustion from the kiln.

In the accompanying drawing an arrangement embodying the invention is illustrated in connection with what is specifically termed herein a cement kiln, which uses coal as a fuel; but it is to be understood that the arrangement may be embodied in other kilns or devices of similar character and with devices where other types of fuel are used.

Fig. 1 is a general view somewhat diagrammatically illustrating a cement kiln with the fuel by-pass arrangement.

Fig. 2 is an enlarged view largely in section, the view being shortened by the center portion of the kiln being removed.

Fig. 3 is a detailed view of a portion of the bypass illustrating the valve and taken substantially on line 3-3 of Fig. 2.

Fig. 4 is a detailed view taken substantially on line 4-4 of Fig. 3 showing the valve arrangement.

Fig. 5 is an tube.

A rotary kiln is illustrated at I having the enlarged detail view of the by-pass usual kiln hood 2 at its lower or front end. The fuel in the form of powdered coal is introduced into the kiln at the kiln hood end through a conduit 3, the coal being passed along, together with air, by means of a fan or blower generally illus- 5 trated at 4. The coal mill is not shown in detail, as devices of this kind are well known to those versed in the art.

At the opposite end of the rotary kiln is a kiln housing 5 and the kiln is fed with raw material 10 at this end, as for example, through the means of an inlet pipe or device 6. The fuel burns in the kiln and the hot gases and products of combustion pass out of the upper end of the kiln into the kiln housing 5. Adjoining the kiln housl5 ing is a boiler l suitably arranged with boiler tubes for the generation of steam by the hot gases issuing from the kiln. The material passing through the kiln from the upper to the lower end may pass out of the hood in the form of clinkers, a passageway for the same being illustrated at 8 which may extend through a supporting floor 9. i

The by-pass for the powdered coal includes a conduit l5 which connects into the conduit 3 preferably angularly as illustrated in Fig. 3. A section It connects onto the section l5, for which purpose the section may have flanges l1 and I8 secured together by rivets 19 with an intervening filler to provide a space for a slide valve memher 20, which may have a hand grip 2| for operating purposes. From the section IS the by-pass comprises a pipe line generaly indicated at 25, the end of which, as illustrated at 26, opens into the kiln housing 5, preferably above the rotary kiln or in the upper portion of the kiln housing. The pipe line may be made up of a plurality of pipe sections, as indicated, and each section may have a small angular pipe section 2'! connecting into it and which may be capped, as shown in Fig. 5, so that access may be had into the pipe line in the case of a plugging up of the pipe line, or other difficulty. The section 15 may have a capped opening 28 for the same purpose.

In some cases where the pipe line 25 is of considerable length, there may be a pressure drop therein, to the end that the coal will not be properly fed therethrough. To meet such a situation, the by-pass may be arranged so that auxiliary air under pressure may be introduced, As shown herein this arrangement is embodied in the section I6 where an auxiliary air inlet pipe is shown at 30, the section I 6 having its walls somewhat of the shape forming a venturi, as illustrated at 3|.

In the use of the apparatus, the powdered coal 5% is fed through the by-pass and discharged into the chamber 5, and the hot gases from the kiln ignites the coal which is fed into the chamber 5. This supplements the heat of the waste gases. The coal by-pass may be entirely shut off by the valve 20 when desired, and the amount of coal by-passed may be regulated by the position of the valve. At times the kiln may be operated with the by-pass closed; at other times when there is a heavy demand for steam and the hot gases from the kiln are insufficient for generating the required steam, the coal is fed through the by-pass and ignited by the hot gases from the kiln and the waste heat thereby supplemented.

I claim:

1. In combination with a cement kiln or the like, means for supplying fuel to the kiln, a boiler positioned to receive products of combustion from the kiln for generating steam, and a fuel by-pass extending from the fuel supply means and arranged to discharge a variable quantity of the by-passed fuel into the products of combustion issuing from the kiln to be ignited thereby to supplement the heat of the products of combustion in generating steam.

2. In combination with a cement kiln or the like, means for supplying fuel to the kiln, a boiler positioned to receive products of combustion from the kiln for generating steam, a fuel by-pass extending from the fuel supply means and arranged to discharge the by-passed fuel into the products of combustion issuing from the kiln to be ignited thereby to supplement the heat of the products of combustion in generating steam, and a valve in the by-pass for controlling the by-passing of the fuel.

3. In combination with a cement kiln or the like, means for supplying coal to the kiln, a boiler positioned to receive products of combustion from the kiln for generating steam, and a conduit constituting a coal by-pass extending from the fuel supply means and arranged to discharge coal into the products of combustion issuing from the kiln to be ignited thereby and supplement the heat of the products of combustion in generating steam.

4. In combination with a cement kiln or the like, means for supplying coal to one end of the kiln, a boiler positioned adjacent the opposite end 5 of the kiln and arranged to receive the products of combustion of the kiln for generating steam, and a conduit constituting a coal by-pass extending from the fuel supply means and arranged to discharge a variable quantity of by-passed coal 1 into the products of combustion issuing from the kiln to be ignited thereby to supplement the heat of the products of combustion in generating steam.

5. In combination with a cement kiln or the 1 like, means for supplying coal to one end of the kiln, a boiler positioned adjacent the opposite end of the kiln and arranged to receive the products of combustion of the kiln for generating steam, a

conduit constituting a coal by-pass extending 20 from the fuel supply means and arranged to' discharge by-passed coal into the products of combustion issuing from the kiln to be ignited thereby to supplement the heat of the products of combustion in generating steam, and a valve in the by-pass operable for the control of the flow of coal therethrough.

6. In combination with a rotary cement kiln or the like, means for supplying powdered coal to one end of the kiln, a housing at the other end of 30 CLINTON P. HARRIS. 

